When Is a Beagle Fully Grown? Growth Stages Explained
If you have a young beagle, you are probably wondering: when do they stop growing? Knowing your beagle’s expected adult size helps with everything from choosing the right harness to planning their exercise routine. This guide covers beagle growth milestones, what influences final size and when you can expect your puppy to reach their full adult weight.
When Do Beagles Stop Growing?
Most beagles reach their full adult height by around 8 months old. However, they continue to fill out — gaining muscle and adult body weight — until they are approximately 18 months old. Some beagles, particularly males, may continue to develop slightly until 2 years of age.
In short: expect your beagle to look physically adult by 12 months, but allow until 18 months for full muscular development. Growth spurts are most dramatic in the first 6 months.
Beagle Growth Chart by Age
Beagles come in two sizes based on the breed standard: the 13-inch variety and the 15-inch variety (measured at the shoulder). Both sizes follow a similar growth curve, just at different final heights and weights.
13-Inch Beagle (under 13 inches at the shoulder)
- 8 weeks: 3–5 kg
- 3 months: 4–6 kg
- 6 months: 6–8 kg
- 9 months: 7–9 kg
- Adult: 8–10 kg
15-Inch Beagle (13–15 inches at the shoulder)
- 8 weeks: 4–7 kg
- 3 months: 6–9 kg
- 6 months: 8–12 kg
- 9 months: 10–13 kg
- Adult: 10–14 kg
For a full breakdown of height, weight and body condition at each age, see our beagle size and weight guide.
Factors That Influence Final Size
Several factors affect how big your beagle will grow:
- Genetics: the size of the parents is the strongest predictor. Ask your breeder about the size of both parents
- Gender: male beagles are typically slightly larger and heavier than females
- Nutrition: correct puppy nutrition supports healthy growth. Overfeeding can cause excessive weight gain, which is not the same as healthy growth
- Health: a puppy that has been unwell may grow more slowly
Is My Beagle Underweight or Overweight?
Growth charts give averages, but individual variation is normal. More important than hitting a specific number is your beagle’s body condition score. You should be able to feel your beagle’s ribs easily without pressing, but not see them visibly. There should be a visible waist when viewed from above.
Beagles are prone to obesity from an early age because of their strong appetite. Monitor their weight monthly and adjust portions as needed. Our beagle weight management guide has practical advice on this.
Puppy Development Milestones
Physical growth is just one part of your beagle’s development. Social and mental development are equally important in the first year:
- 8–12 weeks: critical socialisation window — exposure to different people, sounds, surfaces and animals
- 3–6 months: rapid physical growth, beginning of basic training
- 6–12 months: adolescence begins, sexual maturity, testing of boundaries
- 12–18 months: physical growth slowing, mental maturation continuing
Read our detailed beagle puppy development guide for a week-by-week breakdown of the first year.
When is a beagle fully grown?
Beagles reach their full height by around 8 months and their full adult weight by approximately 18 months. Some males continue to fill out until 2 years old.
How big do beagles get?
The 13-inch variety weighs 8–10 kg at adult size. The 15-inch variety weighs 10–14 kg. Height is measured at the shoulder — under 13 inches for the smaller type, 13–15 inches for the standard size.
Do male beagles grow bigger than females?
Yes, male beagles are typically slightly larger and heavier than females, though the difference is not dramatic.
What should a 6-month-old beagle weigh?
A 6-month-old beagle typically weighs between 6 and 12 kg depending on their size type (13-inch vs 15-inch variety) and gender.
How can I tell if my beagle is a healthy weight?
You should be able to feel the ribs without pressing hard, but not see them clearly. There should be a visible waist when viewed from above. If uncertain, ask your vet.
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